1. Field of the Invention
This invention generally relates to a drum type washing machine including a rotatable tub rotated about a horizontal axis, and more particularly to such a drum type washing machine provided with an improved driving mechanism for driving the rotatable tub.
2. Description of the Prior Art
FIG. 9 illustrates a conventional drum type washing machine. An outer cabinet 1 of the shown washing machine encloses a water tub 2 elastically supported by a plurality of suspension mechanisms 3. A rotatable tub 4 is provided in the water tub 2 to be rotated about a horizontal axis. A bearing housing 6 is screwed to a rear end of the water tub 2. The bearing housing 6 holds two bearings 7 and 8 supporting a rotatable tub shaft 5 of the rotatable tub 4. A driven pulley 9 is mounted on a rear end of the rotatable tub 5. An electric motor 11 is mounted on a motor mount 10 further mounted on a lower circumferential wall of the water tub 2. The motor 11 includes a rotational shaft 12 to which a driving pulley 13 is mounted. A transmission belt 14 extends between the driven pulley 9 and the driving pulley 13.
Upon rotation of the rotational shaft 12 of the motor 11, a rotating force is transmitted via the driving pulley 13, the belt 14 and the driven pulley 9 to the rotatable tub shaft 5, so that the rotatable tub 4 is rotated. However, this transmitting construction increases the number of parts therefor. As a result, the assembling work is complicated and accordingly, the manufacturing cost is increased.
In the washing machine of the above-described type, the driven pulley 9, the driving pulley 13 and the belt 14 produce vibration or oscillation during the transmission of the motor rotating force. In particular, the belt 14 is susceptible to slippage in its portions between it and the driving pulley 13 and between it and the driven pulley 9 when the motor 11 is rotated at high speeds. The belt 14 rocks upon slippage. The rocking of the belt 14 increases the vibration produced by each of the driven pulley 9, the driving pulley 13 and the belt 14, resulting in a loud offensive noise.
Furthermore, the motor 11 is disposed under the water tub 2. This disposition complicates the maintenance of the motor 11 including repair, inspection and replacement thereof. Additionally, when the washing machine is installed on a waterproof pan, a scupper of the pan is sometimes clogged such that a water level in the pan is increased. In this case, there is a possibility that the motor 11 may be exposed to water drops or soaked in water. In view of this drawback, the washing machine needs to be provided with an abnormal water level detector and an electrical protection device. These devices further increase the manufacturing cost of the washing machine.
The washing machine of the above-described type has been provided with detecting means for detecting rotation of the rotatable tub 4. An amount of laundry to be washed, an amount of laundry to be dried and an amount of unbalance of the rotatable tub are determined on the basis of the results of detection by the detecting means. Accuracy in the detection of the detecting means or accuracy in the detection of an amount of laundry to be washed or the like is affected by a tension and slippage of the belt 14 to a large extent. In view of this problem, the tension and dimensions of the belt 14 need to be strictly controlled. This reduces the manufacturing efficiency of the washing machine.